Copper(II) porphyrin-catalyzed coupling of alkyl tosylates and alkyl Grignard reagents afforded substituted alkanes. The role of the copper(II) porphyrin complex was examined using EPR and in-situ synchrotron-based X-ray absorption fine structure measurements. These studies suggested that neither Cu redox nor substitution via in-situ generated cuprate was involved in catalysis. The results supported a reaction mechanism involving single electron transfer from copper(II) porphyrin to tosylate to facilitate the nucleophilic addition of Grignard reagents.